Light emitting diodes (LEDs), because of their unique structure and character of emitting lights, are different from those conventional light sources, and are more applicable to different industrial fields. For example, LEDs are characterized in small size, high reliability, and high output, so they are suitable for many kinds of devices, such as indoor or outdoor large displays. Compared to conventional tungsten lamps, the LEDs work without a filament, consume less power, and respond quicker, so they are widely applied to communication devices or electronic devices. Furthermore, white LEDs have a better illumination effect, a longer lifetime, no harmful material like mercury, a smaller size, and lower power consumption, and therefore the LED devices are advancing in the lamp market.
The operating current of a conventional LED is typically several tens to several hundreds of mAs. Therefore, the brightness of a conventional LED is not suitable for illumination. When lots of LEDs are assembled as an LED lamp to improve the brightness, the volume of the LED lamp is simultaneously multiplied, which results in the loss of its competitiveness. Therefore, to improve the brightness of a single LED is a necessary approach. However, as the LED advances in the market demanding high brightness, the operating current and power of a single LED become several times to several hundred times than those that a conventional LED requires. For example, the operating current of a high brightness LED is about several hundreds of mAs to several amps (A). As a result, the heat generated by the LED becomes an important issue. “Heat” seriously affects the performance of LEDs; for example, the thermal effect will influence the wavelength of lights emitted from the LED, reduce the brightness of lights generated from the semiconductor device, and damage the LED device. Therefore, how to dissipate heat generated by the high power LED determines the development of the LEDs.
When the operating current of LEDs increases, conventional package structures for high power LEDs cannot provide efficient heat dissipation effect. Therefore, there is a need to provide a package structure to dissipate heat generated by LEDs.